In typical automotive air conditioner systems, a clutch is mounted on a compressor in order to intermittently transmit the rotational motion of an automobile engine to the drive shaft of the compressor. Such systems are disclosed in U.S. Pat. No. 5,065,589 to Taguchi and U.S. Pat. No. 5,199,274 to Yoshida et al., both incorporated herein by reference. In such systems, the clutch is controlled in response to the temperature sensed at the evaporator, with the temperature at which the clutch is engaged and disengaged set to fixed temperatures. The temperatures are fixed so that the system will not accumulate ice, no matter what the blower speed. Even though the system can be safely operated at a much colder temperature when the blower speed is on a high setting, the control temperature for the clutch will be fixed to temperature at which the system will safely operate even at the lowest blower speed setting. Therefore, optimum cooling performance is not achieved, especially at high blower speed settings.
U.S. Pat. No. 5,323,619 to Kim discloses a method of controlling the starting patterns of a compressor. In particular, the disclosed method provides for the variation of the starting frequency of the compressor in a combined heating and cooling system. The frequency varies in response to the comparison of the outdoor temperature to a reference temperature.
U.S. Pat. No. 5,199,274 to Yoshida et al. is directed to an air conditioner system having a means to control a compressor in response to the detection of electrical generator saturation. That is, when generator saturation is detected, the compressor speed is decreased thus preventing a sudden drop in the voltage from the generator upon engagement of the clutch which would adversely effect other equipment connected to the generator.